When planning the interior design of an aircraft, it is necessary to know exactly the three-dimensional geometry of the fuselage or fuselage segment in which the interior fittings are meant to be fitted.
So-called laser scans of internal spaces are known from prior public use. Generally, a sphere-shaped scan is carried out here, in which a stationary laser is pivoted about two axes, and the measurement beam scans the internal space in a so-called spherical scan. Information relating to the distance of the reflection site can be obtained either on the basis of the delay time of the reflected measurement beam or, preferably, on the basis of its interference. In an internal space of, for example, an aircraft, which is typically approximately cylindrical, the quality of the measurement points thus obtained varies widely since measurements with a shallow angle of incidence of the measurement beam or a larger distance between location of the laser and point of incidence of the measurement beam typically have a larger error.
Likewise known from prior public use is a so-called profile measurement or profile scan. The measurement beam is, in such a profile measurement, allowed to rotate about only one axis in a plane, the plane typically being perpendicular with respect to the longitudinal axis of the internal space to be measured. The measurement laser is moved during the profile measurements or between profile measurements on said longitudinal axis or parallel thereto. During such a profile scan, the measurement beam generally impinges at right angles or nearly at right angles on the areas to be measured, with the result that an improved measurement quality is attained.